#include<iostream>
#include<unistd.h>
#include<cstdio>
#include<cstring>
#include<sys/types.h>
#include<sys/wait.h>
void Child_write(int wfd)
{
    char buffer[1024];
    int cnt=0;
    while(true)
    {
        snprintf(buffer,sizeof(buffer),"I am child,pid:%d,cnt:%d",getpid(),cnt++);
        write(wfd,buffer,strlen(buffer));
        sleep(1);
    }
}

void FatherRead(int rfd)
{
    char buffer[1024];
    while(true)
    {
        buffer[0]=0;
        ssize_t n=read(rfd,buffer,sizeof(buffer)-1);
        if(n>0)
        {
            buffer[n]=0;
            std::cout<<"child say:"<<buffer<<std::endl;
        }
    }
}

int main()
{
    //1.创建管道
    int fds[2]={0}; //fds[0]:读端  fds[1]:写端
    int n=pipe(fds);
    if(n<0)
    {
        std::cerr<<"pipe error"<<std::endl;
        return 1;
    }
    std::cout<<"fds[0]:"<<fds[0]<<std::endl;
    std::cout<<"fds[1]:"<<fds[1]<<std::endl;
    
    //2.创建子进程
    pid_t id=fork();
    if(id==0)
    {
        //child
        //3.关闭不需要的读写端，形成通信信道
        //f->r,c->w
        close(fds[0]);
        Child_write(fds[1]);
        close(fds[1]);
        exit(0);
    }
    
    //3.关闭不需要的读写端，形成通信信道
    //f->r,c->w
    close(fds[1]);
    FatherRead(fds[0]);
    waitpid(id,nullptr,0);
    close(fds[0]);
    return 0;
}